docs: def _convert_char_to_type(self, type_char):
          """
          Ensures a read character is a typecode.
  
          :param type_char: Read typecode
          :return: The typecode as a string (using chr)
          :raise RuntimeError: Unknown typecode
          """
          typecode = type_char
          if type(type_char) is int:
              typecode = chr(type_char)
  
          if typecode in self.TYPECODES_LIST:
              return typecode
          else:
              raise RuntimeError(
                  "Typecode {0} ({1}) isn't supported.".format(type_char, typecode)
              )